In the field of meat tenderizing apparatus, one well known machine is of the type shown in U.S. Pat. No. 4,437,207 dated Mar. 20, 1984 and U.S. Pat. No. 3,535,734 dated Oct. 27, 1970, both of which issued to Ross. This type of apparatus comprises a plurality of vertical penetrating elements which are held in a head, and caused to penetrate a piece of meat which passes beneath the head. The penetrating elements have knife-edges on the ends thereof and cut the meat fibers as they enter the meat. By arranging the penetrating elements in a particular array, a plurality of small, orthogonal cuts are made in the meat fibers, which tenderizes the meat.
One problem with this type of apparatus becomes apparent when the knife encounters a piece of bone in the meat. When this happens, damage to the machine and the penetrating elements could arise if there were no means for limiting the degree of penetrating force exerted. Thus, the earlier Ross patent provided a way for limiting the penetration force exerted on the meat utilizing a fluid pressure head for holding the penetrating elements. This limited the force to about 3 to 4 pounds of force under operating conditions, before releasing the hold on the penetrating element when it contacted a piece of bone. When a piece of bone was contacted, the contacting element(s) was (were) released so that as the head came down toward the meat, that element or elements was released from the head when the force exceeded the threshold. However with this type of machine, the seals used with the fluid system tend to increase the frictional forces and thus the inserting force.
The later Ross patent provided a different arrangement for limiting the force, in particular a head block with a plurality of magnets mounted therein. Essentially there was one magnet for each penetrating element, and each penetrating element included a portion which served as a pole piece for the associated magnet. The magnets are special magnets made from a cobalt-samarium magnet material, and cooperate with pole pieces made of a special silicon iron alloy. Initially the special magnetic material coupled with the special pole pieces allowed for a rather precise force range to be applied for holding the penetrating elements or knife blades in position in the mounting head, typically on the order of 6-7 pounds of force. However, the head itself is rather bulky, and the design is such that cleaning is somewhat difficult. Small pieces of food are trapped along the shaft of the blade inside the head and trap dirt which tends to build up in the head or on the knife blade. In addition, the pole pieces tend to wear out and/or corrode, so that the limiting force diminishes significantly. Initially the force is about 6 to 7 pounds, but over time diminishes to about 2 pounds or less, rendering the blade functionally useless. Thus the blades are considered expendable parts.
The present invention seeks to provide an improvement in the field of meat tenderizing apparatus, and particularly in the force limiting structure and the associated mounting head for the tenderizing elements.
Accordingly, a primary object of this invention is to overcome the disadvantages of the prior art meat tenderizing apparatus.
Another object of the present invention is to provide an improved force limiting apparatus for a meat tenderizing machine.
Still another object of the invention is to provide an improved head which incorporates an improved force limiting means.
Yet another object of the invention is to provide an improved head for a meat tenderizing machine which can be easily cleaned.
Still a further object of the present invention is to provide an improved head for a meat tenderizing machine with reduced cost and improved simplicity and performance.
Yet a further object of the invention is to provide an improved force limiting apparatus for a meat tenderizing machine which is non-magnetic, non-fluid controlled.
Still another object of the invention is to provide an improved force limiting apparatus for a meat tenderizing machine which is mechanical in nature.